Davit arrangement for raising and lowering a drag



Nov. 16, 1965 F. J. JOYCE 3,

DAVIT ARRANGEMENT FOR RAISING AND LOWERING A DRAG 5 Sheets-Sheet 1 Filed June 28, 1962 INVENTOR. fifmvcls \J. doves Nov. 16, 1965 F. J. JOYCE 3,217,432

DAVIT ARRANGEMENT FOR RAISING AND LOWERING A DRAG INVENTOR.

E e/s 1. doves Ti i Nov. 16, 1965 F. J. JOYCE 3,217,432

DAVIT ARRANGEMENT FOR RAISING AND LOWERING A DRAG Filed June 28, 1962 S'Sheets-Sheet 3 E to K IN VEN TOR. 594005 (1. Joyce- ,4 rropzveys F. J. JOYCE Nov. 16, 1965 DAVIT ARRANGEMENT FOR RAISING AND LOWERING A DRAG 5 Sheets-Sheet 4 Filed June 28, 1962 INVENTOR fiu/vc/s d. doves F. J. JOYCE Nov. 16, 1965 DAVIT ARRANGEMENT FOR RAISING AND LOWERING A DRAG Filed June 28, 1962 m m N dmr mm MA C M w United States Patent 3,217,432 DAVIT ARRANGEMENT FOR RAISING AND LOWERING A DRAG Francis J. Joyce, Morris Plains, N..I., assignor to National Bulk Carriers, Inc., New York, N.Y., a corporation of Delaware Filed June 28, 1962, Ser. No. 205,965 4 Claims. (Cl. 37-72) This invention relates to a novel davit arrangement for use on a dredger in the operation of the draghead which is employed therewith.

Conventional davits contain a long boom which extends diagonally from an anchored position on the ship to an outboard point, thus making possible the raising or the lowering of the draghead along the side of the ship. To maintain the boom in the diagonal position, a vertical support is used. Both the vertical support and boom are quite long and so require considerable head room. A shock absorber is usually dependent from the end of the boom and carries a pulley or sheave upon which the load carrying line is supported. It is attempted to place the shock absorber in alignment with the diagonal force which results from the load on the line and the restraining action of the vertical support on the boom. An indicator is associated with the shock absorber for the purpose of giving a rough approximation of the vertical position of the draghead. In actual practice, the indicator is not only unsatisfactory because of its inaccuracy but also for the reason that it is frequently rendered inoperative by virtue of the shock absorber breaking. Again speaking in practical terms, when the shock absorber is not in alignment with the diagonal force mentioned above, it is vulnerable to breakage, which now happens to an undesirable extent. Consequently, the conventional davits are not satisfactory, because they occupy entirely too much space for the quality of the service which can be expected of them.

Accordingly, an object of this invention is to provide a davit which requires substantially less space on a ship.

Another object of this invention is to provide a novel arrangement of davits by which a draghead can be operated efficiently on a dredger.

Other objects and advantages of this invention will become apparent from the following description and explanation thereof.

The present invention is concerned with a davit having a boom carrying means by which a boom can move inward and outward in a horizontal plane and the carrying means is maintained in an elevated position by virtue of a vertical support means. Such a davit is arranged in combination with two others for the handling of the drag assembly. Each davit contains a line such as a cable or rope which serves to raise or lower a hoist. The line is coiled on a winch, except that in the case of the intermediate davit, each end of the lifting line is connected to a separate winch. The power means which drives the winch of the first davit also powers one of the winches of the intermediate davit, and likewise, the power means which drives the winch of the third davit powers or drives the other winch of the intermediate or second davit. By this arrangement, it is possible to lower, raise or place the draghead in diagonal positions relative to the deck level of the ship as will be explained in greater detail hereinafter.

For a better understanding of the present invention reference will be had to the accompanying drawings which form part of this specification and wherein:

FIGURE 1 is a partial isometric view of a dredger showing the draghead supported aboard ship and the arrangement of three davits associated with it;

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FIGURE 2 is a schematic illustration of the three davits and how the winches associated therewith cooperate with one another;

FIGURE 3 illustrates the technique by which the draghead is lowered into operating position by means of the three davits;

FIGURES 4-9 inclusive illustrate by reference to geometrical symbols how the draghead is lowered into an operating position;

FIGURES 10 and 11 are planar and end views of the davit employed for moving the head of the draghead;

FIGURES 12 and 13 are planar and end views of the davit employed for moving the swivel joint of the'draghead; and

FIGURES 14 and 15 are planar and end views of the davit used to move the trunnion of the draghead.

Referring to the drawings and in particular to FIGURE 1, the trunnion davit 20, the ball joint davit 21 and the head davit 22 are in position for lifting the draghead 26 at the head 23, the ball joint 24 and the trunnion 25, respectively. The draghead 26 rests on spaced deck supports 28 as shown in FIGURE 1, when it is not in operation. In FIGURE 2, the operative relationship among the davits is shown schematically. The head davit 22 has a boom carrier or track 30 supported in an elevated horizontal position by means of vertical members 31 and 32. The vertical members 31 and 32 are fixed to the deck 33 of the ship and are positioned to either side of a hole 34 therein. The boom carrier 30 contains a travelling boom 35 which moves backward and forward in a manner which will be described in greater detail hereinafter. Similarly, the ball joint davit 21 has a boom carrier 36 supported in an elevated horizontal position by means of vertical members 38 and 39 which are fixed to the deck 33 on both sides of a hole 40 therein. The boom carrier 30 supports a travelling boom 41. Likewise, the trunnion davit 20 has its boom carrier 42 supported by vertical members 43 and 44. The travelling boom 46 is supported within the boom carrier 42.

Referring to FIGURE 2, the lifting line or cable 47 of the head davit 22, winds around a winch 48 which is positioned below the deck 33. The cable passes through an opening 49 in the deck 33. The way in which the cable is associated with the davit will be discussed in greater detail hereinafter. The winch 48 is driven by an electrical motor 50 through an interconnecting gear assembly 51. The shaft 52 of the winch is in turn connected to another gear assembly 54 to which is connected a long drive shaft 55 which serves to drive the winch 57 of the ball joint davit 21. The lifting line 58 of the ball joint davit has one end connected to the winch 57 and the other end 59 thereof to a second winch 60. The second winch 60 of the ball joint davit 21 is driven by the drive shaft 61, which is connected to a gear assembly 62 that is driven by motor 63. The same motor 63 drives the winch 64 of the trunnion davit 20. The lifting line 65 of the trunnion davit 20 winds around the winch 64. The manner in which the lifting cables 58 and 65 are associated with the davits 21 and 20, respectively, Will be discussed later.

From the arrangement shown in FIGURE 2, it will be noted that if only one motor is operating, the draghead 26 will be raised or lowered faster at one end than the other, but when both motors 50 and 63 are in operation the draghead can be raised or lowered in a horizontal position. FIGURES 3-9 inclusive serve to illustrate how the manipulation of the draghead can be accomplished to place it in an operative dredging position. From the line diagrams contained in FIGURES 4-6 inclusive, it can be seen that the first step is to drive winches 48 and 57 in order to raise the draghead 26 to a diagonal position above the deck supports 28 as shown in FIGURE 4. The next step is to drive winches 60 and 64 so that the draghead 26 is placed in a horizontal plane in its elevated position. This is illustrated in FIGURES 5 and 6. Once the draghead 26 is in an elevated horizontal position, the davits move it to an outboard position at which the trunnion is in vertical alignment with the pocket or trunnion groove 67 which is located on the side of the ship. Thereafter the head 23 and ball joint 24 are lowered to a diagonal position shown as 68 in FIGURE 3 and corresponds to the line diagram of FIGURE 7. Then the trunnion 25 and the ball joint 24 are lowered to a second diagonal position shown as numeral 69 in FIGURE 3 and the line diagram of FIGURE 8. At this point the trunnion 25 is seated at the bottom of the groove 67. The final step involves lowering the head 23 and the ball joint 24 to the operative position of dredging which is shown as numeral 70 in FIGURE 3 and the line diagram of FIGURE 9. The reverse sequence can be followed in placing the draghead 26 on its back supports aboard ship. Variations of the procedure illustrated in FIGURES 39 inclusive may be made without departing from the scope of this invention.

For a better understanding of the way in which the lifting line 47 is associated with the head davit 22, referonce is to be had to FIGURES l0 and 11. As previously explained, the davit 22 has a boom carrier 30 held in a horizontal position by the vertical supports 31 and 32. The travelling boom 35 is I-shaped and has a channel 72. A series of rollers 73 are rotatably mounted on the inside of the boom carrier 30 and actually support the boom 35 in its horizontal travel back and forth. In FIGURE 11, the boom carrier is shown as two parts 30 and 30a which are held horizontally adjacent to each other by means of cross member 75. The boom is moved by a pinion engaging a rack (not shown) contained in a housing 76 which is turned by the motor 78.

The line 47 originates from an anchor point shown as pin 80. Thence the line extends over the guide pulley 81 before winding around the boom pulley 82 which is rotatably mounted at one end of the boom 35. The line 47 extends horizontally from the pulley 82 to one sheave 83 of a double pulley arrangement which is mounted rotatably in the opposite end of the boom 35. The line 47 then passes down to a block tackle 84 containing two pulleys and is thereafter wound around the both pulleys alternately with the sheaves 83 and 84 of the boom 35. The line leaves the block tackle 84 and passes over another pulley 85 in the boom 35 which is positioned just behind the double pulleys 83 and 84. After passing over pulley 85, the line is guided by a horizontal pulley 87 which is mounted on the cross member 75a, then a horizontal pulley 88 mounted on the top boom carrier part 30, thereafter over the vertical pulley 89 on the side of the boom carrier 30 and finally leading to the winch 48.

FIGURES 12 and 13 are detailed drawings of the ball joint davit 21. As previously indicated, the vertical members 38 and 39 support the boom carrier 36. The vertical members are reinforced by cross members 95 and 96 and the diagonal trusses 97 and 98 which are fastened thereto. The boom 41 is I-shaped and has a channel 100 which engages a series of rollers 101 that are rotatably mounted on the inside of the boom carrier 36. The boom 41 is driven back and forth by means of a pinion engaging a rack (not shown) which is contained in a housing 102 and is driven by a motor 103. The boom carrier is comprised of two parts 36 and 36a which are held apart by means of cross members 105, 106 and 107.

The lift line 58 of the ball joint davit 21 shown in FIGURES 12 and 13 is arranged to be wound on the winches 57 and 60. Line 58 passes over the sheave 109 which is mounted on the outside of boom carrier 36a as shown in FIGURE 13. Thereafter it passes around the pulley 110 which is mounted horizontally from a dependent position from the cross member 107. The line 58' passes at a right angle around the sheave 110 and passes to the sheave 111 of a double pulley arrangement 112 at the front part of the boom 41. The line then passes downwardly around a sheave 114 of the block tackle 115 and then upwardly again to wrap around the other sheave 116 of the double pulley 112 which is supported in the boom 41. The line 58 goes downwardly again to wrap around the second sheave (not shown) of the block pulley 115 before traversing upwardly to wrap around the sheave 117 which is adjacent but to the rear of the double pulley 112 in the front part of the boom 41. The line changes its course and runs along the top of the boom 41 and wraps around a sheave 118 which is supported within a recess 119 at the other end of the boom 41. The line 58 then travels inwardly toward the support 38 to engage a guide pulley 121 and then over the top of an adjacent sheave 122 which guides the line downwardly as line 59 which is associated withwinch 60.

The details of the trunnion davit 20 are given in FIGURES 14 and 15. The vertical members 43 and 44 are reinforced by cross members 125 and 126 and the diagonal trusses 127 and 128 which are connected thereto. The boom carrier 42 supports the boom 46 by means of rotatably mounted rollers 130 on the inside thereof which engage the channel 131 of the boom 46. The boom 46 is moved back and forth by a pinion engaging a rack (not shown) contained in a housing 132 which is powered by a motor 133. The boom carrier comprises parts 42 and 42a which are held apart by means of cross members 135 and 136.

The lifting line 65 is anchored to the vertical support 43 as shown by the pin 137. The line then engages the underside of a small guide pulley before wrapping around a main pulley 141 which is mounted on the side of the boom 46 at one end thereof. The line travels from the sheave 141 horizontally along the top of the boom 46 and then engages the upper peripheral side of a pulley 143 which is mounted on the boom 46 at other end thereof. The line passes over the pulley 143 and downwardly for engagement with a pulley 144 of a double pulley block tackle 145. The line then passes upwardly and wraps around the top of a second pulley 146 which is positioned adjacently at an angle to the pulley 143. The line passes downwardly again to wrap around the second pulley 147 of the block tackle and then upwardly to pass around the top of another pulley 148 before travelling horizontally along the top of the boom 46. A horizontal pulley 149 is positioned at the other end of the boom to receive the line and direct it toward a vertical pulley 150, which is supported at the outside of boom carrier 42a. The line then passes downwardly for engagement with the winch 64.

I claim:

1. A system for raising and lowering a drag comprising a trunnion, a ball joint, and a head, said system comprising: a trunnion davit; a ball joint davit; a head davit; support means for supporting all of said davits rigidly with respect to each other; a substantially horizontal boom on each of said davits; sheaves at both ends of each boom; a first lifting line running over the sheaves on the boom on said head davit to support said head from said head davit, one end of said line being fixedly connected with respect to said head davit; a second lifting line running over the sheaves on the boom on said ball joint davit to support said ball joint from said ball joint davit; and a third lifting line running over the sheaves on the boom on said trunnion davit to support said trunnion from said trunnion davit, one end of said third line being fixedly connected with respect to said trunnion davit; a first winch connected to the other end of said first lifting line to raise and lower said head; first drive means connected to said winch for driving the same; second and third winches connected, respectively, to the two ends of said second line for raising and lowering said ball joint; a fourth winch connected to the other end of said third lifting line for raising and lowering said trunnion; drive means connected to said fourth winch for operating the same; a driving connection between said first winch and said second winch to drive said second winch simultaneously with said first winch to wind one end of said second line at a predetermined rate with respect to the rate at which said first line is wound on said first winch when said first driving means is energized, the relative rate of winding being determined by the fraction of the length of said drag between said head and said ball joint in proportion to the total length of said drag whereby said drag is maintained substantially straight while said head is being moved relative to said trunnion; and a second driving connection between said fourth winch and said third winch to drive both of said winches simultaneously, to wind the other end of said second line at a predetermined rate with respect to the rate at which said third line is wound on said fourth winch when said second driving means is energized, the relative rate of winding being determined by the fraction of the length of said drag between said trunnion and said ball joint in proportion to the total length of said drag whereby said drag is maintained substantially straight while said trunnion is being moved relative to said head.

2. The system of claim 1 in which each of said booms is movable in a substantially horizontal direction along said davit and substantially parallel to each of the others of said booms; and each of said davits comprises driving means to move the respective one of said booms in its substantially horizontal direction of motion.

3. The system of claim I in which one end of said first lifting line is fixedly attached to said head davit and the other end of said first line is wrapped around said first winch, one end of said third line is fixedly attached to said trunnion davit and the other end of said third line is wrapped around said fourth winch, and one end of said second line is wrapped around said second winch and the other end of said second line is wrapped around said third winch to permit said second line to be operated by both said first drive means and said second drive means.

4. The system of claim 3 comprising gear means between said first winch and said second winch and separate gear means between said third winch and said fourth winch, both of said gear means and all of said winches being related in diameter to permit said drag to be kept substantially straight while either said trunnion or said head is being raised or lowered.

References Cited by the Examiner UNITED STATES PATENTS 695,067 3/1902 Mallon 935 1,900,905 3/1933 Bowden 935 2,651,122 9/1953 Brinkman 3772 FOREIGN PATENTS 123,950 of 1919 Great Britain.

657,181 9/ 1951 Great Britain.

CHARLES E. OCONNELL, Primary Examiner.

ROBERT C, RIODON, BENJAMIN HERSH, Examiners. 

1. A SYSTEM FOR RAISING AND LOWERING A DRAG COMPRISING A TRUNNION, A BALL JOINT, AND A HEAD, SAID SYSTEM COMPRISING: A TRUNNION DAVIT; A BALL JOINT DAVIT; A HEAD DAVIT; SUPPORT MEANS FOR SUPPORTING ALL OF SAID DAVITS RIGIDLY WITH RESPECT TO EACH OTHER; A SUBSTANTIALLY HORIZONTAL BOOM ON EACH OF SAID DAVITS; SHEAVES AT BOTH ENDS OF EACH BOOM; A FIRST LIFTING LINE RUNNING OVER THE SHEAVES ON THE BOOM ON SAID HEAD DAVIT TO SUPPORT SAID HEAD FROM SAID HEAD DVIT, ONE END OF SAID LINE BEING FIXEDLY CONNECTED WITH RESPECT TO SAID HEAD DAVIT; A SECOND LIFTING LINE RUNNING OVER THE SHEAVES ON THE BOOM ON SAID BALL JOINT DAVIT TO SUPPORT SAID BALL JOINT FROM SAID BALL JOINT DAVIT; AND A THIRD LIFTING LINE RUNNING OVER THE SHEAVES ON THE BOOM ON SAID TRUNNION DAVIT TO SUPPORT SAID TRUNNION FROM SAID TRUNNION DAVIT, ONE END SAID THIRD LINE BEING FIXEDLY CONNECTED WITH RESPECT TO SAID TRUNNION DAVIT; A FIRST WINCH CONNECTED TO THE OTHER END OF SAID FIRST LIFTING LINE TO RAISE AND LOWER SAID HEAD; FIRST DRIVE MEANS CONNECTED TO SAID WINCH FOR DRIVING THE SAME; SECOND AND THIRD WINCHES CONNECTED, RESPECTIVELY, TO THE TWO ENDS OF SAID SECOND LINE FOR RAISING AND LOWERING SAID BALL JOINT; A FOURTH WINCH CONNECTED TO THE OTHER END OF SAID THIRD LIFTING LINE FOR RAISING AND LOWERING SAID TRUNNION; DRIVE MEANS CONNECTED TO SAID FOURTH WINCH FOR OPERATING THE SAME; A DRIVING CONNECTION BETWEEN SAID FIRST WINCH AND SAID SECOND WINCH TO DRIVE SAID SECOND WINCH SIMULTANEOUSLY WITH SAID FIRST WINCH TO WIND ONE END OF SAID SECOND LINE AT A PREDETERMINED RATE WITH RESPECT TO THE RATE AT WHICH SAID FIRST LINE IS WOUND ON SAID FIRST WINCH WHEN SAID FIRST DRIVING MEANS IS ENERGIZED, THE RELATIVE RATE OF WINDING BEING DETERMINED BY THE FRACTION OF THE LENGTH OF SAID DRAG BETWEEN SAID HEAD AND SAID BALL JOINT IN PROPORTION TO THE TOTAL LENGTH OF SAID DRAG WHEREBY SAID DRAG IS MAINTAINED SUBSTANTIALLY STRAIGHT WHILE SAID HEAD IS BEING MOVED RELATIVE TO SAID TRUNNION AND A SECOND DRIVING CONNECTION BETWEEN SAID FOURTH WINCH AND SAID THIRD WINCH TO DRIVE BOTH OF SAID WINCHES SIMULTANEOUSLY, TO WIND THE OTHER END OF SAID SECOND LINE AT A PREDETERMINED RATE WITH RESPECT TO THE RATE AT WHICH SAID THIRD LINE IS WOUND ON SAID FOURTH WINCH WHEN SAID SECOND DRIVING MEANS IS ENERGIZED, THE RELATIVE RATE OF WINDING BEING DETERMINED BY THE FRACTION OF THE LENGTH OF SAID DRAG BETWEEN SAID TRUNNION AND SAID BALL JOINT IN PROPORTION TO THE TOTAL LENGTH OF SAID DRAG WHEREBY SAID DRAG IS MAINTAINED SUBSTANTIALLY STRAIGHT WHILE SAID TRUNNION IS BEING MOVED RELATIVE TO SAID HEAD. 